# Heating and Cooling Curve of Water

## Heating and Cooling Curve of Water

• Submitted By: nickchia
• Date Submitted: 02/23/2011 9:58 AM
• Category: Science
• Words: 577
• Page: 3
• Views: 1

Objectives
By changing the states of matter of water, using a Data Logger, our objective was to observe the heating and cooling curve of water.
To Read and interpret meaning from graphs, charts, and tables

Materials
-200 cm3 Beaker
-Test tube
- Clamp
- Stand
- Data Logger
- Thermometer
- Probe
- Salt (NaCl)
- Stopwatch
- Ice
- 10 cm3 Measuring cylinder
- Stirring rod
- Polystyrene cup

Introduction
In Chemistry there are three states of matter: solid, liquid and gas. Water is a good example to observe closely the transition from one state to another, when heat is applied ice becomes water ( melting) and water becomes gas (evaporation) . Sometimes a solid can directly become a gas (sublimation). When water undergoes low temperature, it becomes a solid (freezing). Salt, or sodium chloride, is a useful substance to lower the freezing point of water and other substances. For this reason we have used salt in our experiment, in order to freeze the water.

Hypothesis
In these experiments, unless sistematic errors will occur, I will observe the shifting states of water and hopefully the distilled water in the test tube will freeze, but melt after less than two minutes because of the outside temperature.
Maybe our group will also witness “ supercooling” is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid.

Procedure
Freezing
- Fill a 200 cm3 beaker 1/3 full with ice, then add enough tap water to cover the ice. This is an “ice water bath”
- Using the measuring cilinder put 5 cm3 of distilled water into a test tube.
- Use a Utility clamp to fasten the test tube to a stand. The test tube should be camped above the water bath. Place the probe into the water inside the test tube.
- Lower the test tube into the “ice-water” bath. Record the temperature of the water from now on.
- Soon after lowering the test tube, add 5 tablespoons of salt to the beaker and stir with a...